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  1. #1
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    Truvativ Howitzer bearing size/fitment?

    I jumped on a new set of Hussefelt cranks for my RM7 build as they were very cheap. At the time I bought them I could have sworn the ad said they would work for any ISIS BB. Well turns out they are the Howitzer interface. I'm wondering if anyone with a Howitzer BB setup can tell me how much bigger the bearing housing is than their BB tube on the frame?

    Reason I ask is the RM7's main pivot is very close to the BB and I'm worried fitment will be an issue. If anyone can give me some pics showings their Howitzers installed that would be great and much appreciated!!! Or if anyone has experience fitting one of these on an RM7 any insight would be helpful!

    *i attached a pic showing the clearance for reference.

    Thanks in advance!

    Robbie
    Attached Thumbnails Attached Thumbnails Truvativ Howitzer bearing size/fitment?-image.jpg  


  2. #2
    ...for I am a raindog too
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    Using a Shimano ext. bb and a howitzer as a test group--- you will likely be fine. Neither is significantly bigger than the diameter of the bb shell on either bike.

    About the best you can do is to order the bb and if it doesn't fit, you can sell the bb and crank as a set.
    If you are lonely when you're alone, you are in bad company

  3. #3
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    i have both shimano xtr and the howitzer. the xtr are in there now, same bearing cup diameter, just the cups arent are deep. it is extremely tight, as in, less then a millimeter of space with it on the stand.

  4. #4
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    Echo24, do you have that BB installed in a RM-7 Frame? Could I get a pic or 2 of your fitment?

  5. #5
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    Also, on price point the option they offer is 68/73x51mm. How do these bb's do their measurements? I'm just use to the spindle length, not the chain line measurement. I'm not sure if the 68/73x51 will work? I plan on running 1x8 drivetrain.

  6. #6
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    Quote Originally Posted by Subydrift View Post
    Echo24, do you have that BB installed in a RM-7 Frame? Could I get a pic or 2 of your fitment?
    here you go buddy. first photo is before i ran the cups in. changed out my xtr cranks for the truvativs. theyll hold up better to what i want to do.







    im running holtzfeller cranks and still have good spacing between the arm and swingarm without any spacers


  7. #7
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    Those pics are extremely helpful! Thank you! It's hard to tell from the pics but is there contact between the bearing and swing arm? Did the bearing thread in fine past the swing arm? I just ordered a bb off eBay so I'm gonna give it a shot. If it doesn't fit I'll probably just install the bearing with the swing arm off and file the bearing housing down where the swing arm contacts.

  8. #8
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    i didnt see the swingarm scratch the bearing but like i said it is a very tight space. it spun in with no sounds of rubbing or any added resistance.

  9. #9
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    Good to know man thanks a ton! Do you by chance know what size your bb is? I ordered a 51mm chain line version cause I read that is equivalent to a 118 spindle??? I hope that's gonna work! Lol.

  10. #10
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    i have the 68/73mm bb which is the 51mm chainline based off chainreaction

  11. #11
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    Perfect. Thanks for your help!

  12. #12
    life on 2 wheels
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    no prob

  13. #13
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    On a positive note, the bearings are the same from the 51mm to 56mm, the bearings have a cap with a larger spacer that comes off easily so in the event you needed the larger size, you can just use the bearings assuming you axle is still in fine shape. I took a chance and ordered both sizes when BlueSky was blowing them out last year and they move easily to each other.

  14. #14
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    alright got my front wheel today and took the bike around the block to see what i need for final tweaks. and the bearings are too big. as in 1mm too big and it rubs the swingarm. it basically took the powdercoat off. so i popped the bearing off and filed a small bit off the cup (doesnt take much) from the area where it touches. much better movement.

  15. #15
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    echo24, thanks for the update! Mine should be here within the next couple days. I'll probably sand the powdercoat off the swingarm right there and then thread the bearing in and mark where it could interfere and throw it in the vice and file it away a little bit also.

    Have you pulled your back wheel and rear shock off and moved the swingarm by hand to see if you feel any friction still? I'm not to worried about the little filing and sanding tweaks to make it work as its a much burlier setup then a regular ISIS BB. I just don't want it to be binding and hindering the movement of the swingarm.

    I am a front wheel and brakes away from finishing my RM7 DH build! What are the specs of your build Echo24?

    Also, could you attach a pic showing what you did to yours? Thanks.

    Robbie
    Last edited by Subydrift; 12-06-2012 at 08:26 AM.

  16. #16
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    i havnt taken the wheel and shock off to check for movement, i can normally hear things like that and feel it in the bike. but after i filed off the bb (i just did the location where it lines up with the swing arm) and threading it in, i could tell i freed up some space. and from what little bit of riding i did, i couldnt feel or sense any binding, and if there is, itll work itself out :P

    spec wise, 888vf, mtx 31 front hoop, fundamental rear, ns roller hubs, ns terra bars, nukeproof direct mount stem, truvativ holtzfeller dh cranks, boxguide with some modifactions, xtr shifting, avid code r 160 out back hope mono 4 205 up front (waiting on adapter). i was trying for an ns component build since i like their stuff (have a hardtail build ns and atomlab build and havnt had any problems) but chainreaction didnt have everything i wanted a few weeks back.

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